- A dry process of separating placer gold; the rapid disposal of heavy snows in cities.
- Experiments on flying machines with an engine operated by explosions of guncotton.
- The joint invention, with M. W. Scott Sims, of a dirigible submarine torpedo operated by electricity.
- Pyromagnetic generators for generating electricity directly from the combustion of coal.
- Pyromagnetic motors operated by alternate heating and cooling.
- A magnetic bridge for testing the magnetic qualities of iron.
- A "dead-beat" galvanometer without coils or magnetic needle.
- The odoroscope, for measuring odors; preserving fruit in vacuo; making plate glass; drawing wire.
- Metallurgical processes for treatment of nickel, gold, and copper ores.
From first to last Edison has filed in the United States Patent Office more than fourteen hundred applications for patents. Besides, he filed some one hundred and twenty caveats, embracing not less than fifteen hundred additional inventions. The caveat has now been abolished in patent-office practice, but such a document could formerly be filed by an inventor to obtain a partial protection for a year while completing his invention. As an example of Edison's fertility and the endless variety of subjects engaging his attention the following list of matters covered by one of his caveats is given. All his caveats are not quite so full of "plums," but this is certainly a wonder:
- Forty-one distinct inventions relating to the phonograph, covering various forms of recorders, arrangement of parts, making of records, shaving tool, adjustments, etc.
- Eight forms of electric lamps using infusible earthy oxides and brought to high incandescence in vacuo by high potential current of several thousand volts; same character as impingement of X-rays on object in bulb.
- A loud-speaking telephone with quartz cylinder and beam of ultra-violet light.
- Four forms of arc-light with special carbons.
- A thermostatic motor.
- A device for sealing together the inside part and bulb of an incandescent lamp mechanically.
- Regulators for dynamos and motors.
- Three devices for utilizing vibrations beyond the ultra-violet.
- A great variety of methods for coating incandescent lamp filaments with silicon, titanium, chromium, osmium, boron, etc.
- Several methods of making porous filaments.
- Several methods of making squirted filaments of a variety of materials, of which about thirty are specified.
- Seventeen different methods and devices for separating magnetic ores.
- A continuously operative primary battery.
- A musical instrument operating one of Helmholtz's artificial larynxes.
- A siren worked by explosion of small quantities of oxygen and hydrogen mixed.
- Three other sirens made to give vocal sounds or articulate speech.
- A device for projecting sound-waves to a distance without spreading, and in a straight line, on the principle of smoke-rings.
- A device for continuously indicating on a galvanometer the depths of the ocean.
- A method of preventing in a great measure friction of water against the hull of a ship and incidentally preventing fouling by barnacles.
- A telephone receiver whereby the vibrations of the diaphragm are considerably amplified.
- Two methods of "space" telegraphy at sea.
- An improved and extended string telephone.
- Devices and method of talking through water for a considerable distance.
- An audiphone for deaf people.
- Sound-bridge for measuring resistance of tubes and other materials for conveying sound.
- A method of testing a magnet to ascertain the existence of flaws in the iron or steel composing the same.
- Method of distilling liquids by incandescent conductor immersed in the liquid.
- Method of obtaining electricity direct from coal.
- An engine operated by steam produced by the hydration and dehydration of metallic salts.
- Device and method of telegraphing photographically.
- Carbon crucible kept brilliantly incandescent by current in vacuo for obtaining reaction with refractory metals.
- Device for examining combinations of odors and their changes by rotation at different speeds.
It must be borne in mind that the above and hundreds of others are not merely ideas put in writing, but represent actual inventions upon which Edison worked and experimented. In many cases the experiments ran into the thousands, requiring months for their performance.
To describe Edison's mere ideas and suggestions for future work would of itself fill a volume. These are written in his own handwriting in a number of large record-books which he has shown to the writer. Judging from a hasty inspection, there is enough material in these books to occupy the lifetime of several persons.
The immense range of Edison's mind and activities cannot well be described in cold print, but can only be adequately comprehended by those who have been closely associated with him for a length of time, and who have had opportunity of studying his voluminous records.
XXIII
EDISON'S METHOD IN INVENTING
If one were allowed only two words with which to describe Edison it is doubtful whether a close examination of the entire dictionary would disclose any others more suitable than "experimenter-inventor." These would express the overruling characteristics of his eventful career.